The right foot (first three images) shows an inhomogeneous thin linear lucency at the base of the right fifth metatarsal bone reaching the cortical surface. The irregularity and transverse orientation, both indicate that this is an avulsion fracture instead of an unfused apophysis.

The comparison view of the contralateral, uninjured foot (last two images) provides further evidence (note that the age of the patient coincides with the expected fusion of the apophysis).